Study on human alertness affected by dynamic trend of lighting

With the development of LED light technology, LED dynamic lighting is on the way to become the mainstream of office lighting. This paper studied the impact of changing trends of dynamic lighting parameters on alertness in different periods, hoping to provide a reference for future office dynamic light design. 24 participants took part in the experiment using 9 conditions (4 conditions in the morning, 5 conditions in the afternoon) of dynamic light with each observing session lasting from 09:00 to 11:30 or from 13:00 to 17:00. Karolinska Sleepiness Scale (KSS) was used to evaluate the alertness of subjects. The results showed that participants felt more alert under the increasing illuminance and CCT oscillation in the morning, with a significant difference comparing with static light (dKSS = -0.56, p<0.01). Among the afternoon condition, the dynamic lighting with the decreasing illuminance and the increasing colour temperature showed the most alertness promotion (dKSS = -0.70, p<0.01).